1. Field of Invention
This invention relates to a method of encoding, and in turn reliably decoding, embedded data blocks containing occlusions having any variable size and shape within an embedded data block.
2. Description of Related Art
It is often desirable to have a document contain not only human readable information, but also machine readable information. For example, a check may desirably contain machine readable identification verification.
An example of such machine readable information is a bar code. However, bar codes are obtrusive and not esthetically pleasing in a document. Therefore, self-clocking glyph codes have been developed in order to embed digitized information within a document in an esthetically pleasing manner. One of the principal advantages of self-clocking glyph codes is that they tend to be esthetically pleasing because of their non-obtrusive visual appearance.
The data is embedded into a data glyph block, which is rendered onto a recording medium by any number of known techniques. The rendered data block typically looks like a uniformly shaped, monochromatic (for example, gray) or polychromatic area upon the recording medium. The data symbols, or glyph marks, in the data glyph block are unobtrusive to the unaided human eye.
To make the embedded digital information even less obtrusive in the document, it would be desirable to be able to permit a user to intentionally include other human visible/readable information within the data block, for example to include logos, icons, graphics, text, marks or other objects within the embedded data block. The embedded data block would thus appear to be background to the human visible/readable information within the embedded data block.
This invention achieves a method for permitting embedded data blocks to include intentional occlusions, for example human visible/readable information such as logos, icons, graphics, text, marks or other objects, within a data glyph block.
In particular, the invention achieves a method of encoding an embedded data block containing occlusions within the embedded data block such that the occluded embedded data block can be readily and reliably decoded from the recording media.
More in particular, the invention achieves a method of encoding occlusions within an embedded data block, comprising determining the size and location of an occlusion comprised of one or more occluded areas within the embedded data block, determining a regular polygon shape that encompasses only occluded areas of the occlusion, thereby separating the occlusion into occluded areas within the regular polygon shape and remainder occluded areas, if any, outside of the regular polygon shape, directly encoding the regular polygon shape with synchronization lines, and indirectly encoding any remainder occluded areas with error correction.